“Iran is a geographically and strategically important economy with much potential and it makes sense for the UK to have a solid future business, political and economic relationship with it,” Gerard Lyons, chief economic advisor to the Mayor of London told The Telegraph.

British oil and gas companies are expected to be the major benefactors from a thawing of relations between Tehran and the West. Existing sanctions are due to be reviewed on June 20 and it is expected to result in an easing of restrictions on the oil and gas, and petrochemicals industries.

“Companies have been preparing for re-entry over recent months,” said Tom Stocker, an energy specialist at law firm Pinsent Masons. “Iran is rich with natural resources and was once one of the key providers of petrochemicals to the European markets. At such a pivotal time for our domestic energy supply and global resources, oil and gas companies are assessing alternative access to fossil fuels as the threat of sanctions on Russia becomes a genuine concern.

Iran’s Oil Minister Bijan Namdar Zanganeh has set a new output target of 5.7 million barrels per day (bpd) of crude by 2018, according to official statements. The latest figures produced by the Organization of Petroleum Exporting Countries (OPEC) show that Iran is currently pumping about 3 million bpd of crude.

In addition to a range of trade sanctions imposed by the U.S. in 2010, the European Union banned the import, purchase, and transportation of Iranian crude oil as well the construction of oil tankers for the Islamic Republic, which has been locked in a long-running dispute with the West over its nuclear program.

“Iran re-entry presents an opportunity to improve security of supply and for oil and gas service companies to develop significant opportunities,” said Mr. Stocker.

However, speaking on Tuesday, Mr. Hague dampened expectations of an immediate easing of Britain's position on Iran.